The brake pads and rotors are pretty much the same as any other car. The sensor just clips into the pad... you'll see when you take it apart. The minimum thickness is stamped on the rotor. As for the aux input, it sounds like you have a control module (ULF-SBX) failure. Someone would have to pull the faults to be sure though, if a software update doesn't reboot it, than it may have to be replaced.